Bill McMillan generously shared the documents below on his ongoing study of the Mid-Skagit tributaries. Bill has tirelessly conducted spawning surveys on these tributaries and he has collected, graphed, and interpreted this data through scientific methods. Of note is the presence of hatchery steelhead on the spawning grounds in these tributaries and also significant spawning activity before the supposed March 15 timeline of supposed wild steelhead spawning commencement. My hope is that the evidence in this study will be a harbinger of further wild steelhead recovery on the Skagit with the complete cessation of hatchery plants.
Kudos and much gratitude to Bill for his dedicated study of wild steelhead on the Skagit, and beyond, and for his immeasurable contributions to wild steelhead conservation.
Links to the documents provided below and I've copied over the summary of Bill's draft.
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McMillan, B. 2015. The Reproductive Ecology of Oncorhynchus mykiss in Tributary Streams of the Mid Skagit River Basin.
Kudos and much gratitude to Bill for his dedicated study of wild steelhead on the Skagit, and beyond, and for his immeasurable contributions to wild steelhead conservation.
Links to the documents provided below and I've copied over the summary of Bill's draft.
--------------------
McMillan, B. 2015. The Reproductive Ecology of Oncorhynchus mykiss in Tributary Streams of the Mid Skagit River Basin.
The information provided is pertinent to the present public process
related to the Draft Environmental
Impact Statement (DEIS) on Two Joint State and Tribal Resource Management
Plans for Puget Sound Salmon and Steelhead Hatchery
Programs. Some of
those who provide comments to the DEIS will be citing this Summary (and
the report it represents).
The 2010-2014 Mid Skagit tributary spawning
surveys were independently done by me as a retired field biologist
(Wild Fish Conservancy for 10 years) motivated by both a personal and
scientific interest of living on the Mid Skagit River in
order to fill a temporal void in steelhead spawning information
that I knew existed. There was no funding provided by anyone.
This void in steelhead spawning information has long existed in much
of Western Washington and has resulted in much misunderstanding about the life
histories of wild winter-run steelhead and their sharing of spawning
habitat with feral Chambers Creek hatchery steelhead.
https://www.academia.edu/10197391/Reproductive_Ecology_of_O._mykiss_in_Tributary_Streams_of_Mid_Skagit_River_Basin_Final_Summary_1-16-2015
The Reproductive Ecology of Oncorhynchus mykiss
in Tributary Streams of the Mid Skagit
River Basin
(A Final Summary with the full report still in Draft form)
Bill McMillan
(January 15, 2015)
40104 Savage Road
Concrete, WA 98237
| Acknowledgments: In great appreciation for the several reviews and helpful comments provided by George Pess of NOAA’s Northwest Fisheries Science Center in the drafting of the Summary and the full report it represents; to Nora Kammer of Skagit River System Cooperative tribes for Savage Creek pond observations; and to Brett Barkdull of Washington Department of Fish and Wildlife for a 2014 Skagit basin steelhead spawning escapement estimate. | |
Summary
From October of 2009 to June of
2014 regular spawning surveys were independently and voluntarily made for
personal fishery interests as a retired field biologist at five Mid Skagit
basin tributary streams that support the spawning of the anadromous life
history of Oncorhynchus mykiss (O. mykiss) commonly known as
steelhead. The most intensive of these
five years of surveys were those from October 2013 to June of 2014 with a total
of 125 spawning surveys made at these five tributaries. Puget Sound Steelhead in Washington are
listed under the Endangered Species Act (ESA) as Threatened, including those of
the Skagit River basin. Several and
perhaps all of the same tributaries also support resident
O. mykiss populations commonly known
as rainbow trout. All of the same
tributaries also have spawning populations of coho salmon (O. kisutch) and pink salmon (O.
gorbuscha)
as well as coastal cutthroat trout (O. clarki clarki) of
both anadromous and resident life histories.
Four of the streams also have spawning chum salmon (O. keta) and three have spawning returns of ESA listed Chinook
salmon (O. tshawytscha).
Winter steelhead spawning surveys
in the Skagit basin by Washington Department of Fish and Wildlife (WDFW) have
targeted an initiation time of March 15th in the supposition that is
when wild steelhead begin to spawn. In
fact, management of winter steelhead has been based on the belief that hatchery
steelhead spawn prior to March 15th and wild after with little
potential for spawning interactions between the two to occur. However, no recent history was found of
steelhead spawning surveys that regularly occurred prior to March 15th
from which to justify this conclusion in the Skagit basin. Historic evidence from the early 1900s
indicates Skagit basin winter steelhead began to spawn by early February and
Mid Skagit tributary entry for spawning began by January. On the Northwest Coast of Washington where
spawning surveys were initiated in January by Washington Department of Natural
Resources (WDNR) from 1973 to 1980, and similarly so during independent surveys
by the Wild Salmon Center (WSC) from 1999 to 2003, it was found that wild
winter steelhead spawning begins by early January. Other areas of the Pacific Northwest also
exhibit early steelhead spawning. For instance, the State of Oregon’s spawning
survey protocol for coastal rivers is from mid-January through mid-May. In British Columbia wild winter steelhead
spawning historically began as early as January on central Vancouver Island and
in more recent history by January or February at least as far north as the
Queen Charlotte Islands and Southeast Alaska.
The 2009-10 to 2013-14 spawning
surveys at the five Mid Skagit tributaries were initiated with the first fall
storms that stimulate the upstream migration of anadromous spawning runs. This was to insure that no steelhead spawning
was missed and to determine what the overlaps between steelhead spawning time
with other salmonids may be. Over the
five years the
earliest steelhead spawning redd
found was January 16th and the latest June 6th. Coho salmon and steelhead were found to have
slight overlapping spawning times some years but it was
typically minimal. Sea-run and resident cutthroat were found to
have significant spawning time overlaps with steelhead. Hatchery steelhead were included in the O. mykiss spawning population mix and
steelhead mating (both wild and feral hatchery) included wild resident male
life histories.
There were 104 total steelhead
redds counted in the five years of Mid Skagit tributary surveys (Table 1). Almost half (49%) of the redds were found
prior to March 15th, the assumed initiation date of wild steelhead
spawning. Over half (53%) of the
steelhead were estimated to have spawned prior to March 15th when
redd sightings were adjusted for spawn timing (Figure 1). In the five years of surveys a total of 18 O. mykiss (14 steelhead, 2 male
residents, and 2 undetermined male steelhead or residents) were observed at 7
active spawning redds between January and June (Table 2). The hatchery proportion of the steelhead in
the spawning mix was 40%. If the wild
male resident life history was included it decreased to 33% hatchery. Both wild and hatchery origin steelhead were
found spawning in the early time period of January to mid March. The hatchery proportion of the steelhead
spawning mix prior to March 15th was 67% (Table 3). If the wild male resident life history was
included it decreased to 50% hatchery. Although no hatchery steelhead were
found spawning after March 15th the unknown origin steelhead after
that date were 20% of the total steelhead observed. Of particular concern, hatchery steelhead
were found spawning to the maximum upstream anadromous extent of the smallest
tributaries in the Mid Skagit basin.
The spawning time of steelhead was
found to vary between tributaries. Over 50% of the spawning occurred prior to
March 15th in three of the tributaries. The two other tributaries
had 50% of the spawning occurring after March 15th. Air/water temperature, precipitation,
streamflow, and intermittent or perennial hydrology were all examined as
potential explanations for the spawn timing differences. Streamflow hydrology best explained the
steelhead spawn timing differences. Specifically, whether a tributary’s
hydrology was intermittent or perennial was found to be a particularly probable
driver regarding whether most steelhead spawned prior to March 15th
or most thereafter (Figure 3). This was
hypothesized to be due to the need for spawning to be early enough for
significant numbers of emergent steelhead fry to move either downstream to
perennial waters prior to late June to early July when intermittent flows began
to disconnect these tributaries from larger downstream water bodies, or
upstream if that option were available. Although intermittency is predicted to
increase in northward expansion with climate change, and is sometimes perceived
as a great limitation on steelhead reproductive success, there are examples of
high steelhead productivity that occurs in intermittent streams and where
gravel accumulations may actually provide better spawning habitat if steelhead
life histories have effectively adapted with early spawning and emergence.
From the limited specific
tributary water temperatures taken, the coldest stream had the latest steelhead
spawn timing and the four warmer streams earlier. At the cumulative level of
all five tributaries a highly significant correlation was found between average
monthly air temperature and steelhead redds per month when adjusted to spawning
date if 50-67% of the redds during the early spawning period were eliminated to
better reflect wild steelhead spawning (Figure 2). Spawn timing also varied by
year. In one tributary with significant spawners in 2010 and 2014 the warmer
year (2010) had a month earlier spawning peak than the colder year (2014). Active spawning was found to most commonly
occur shortly after a flow peak on a falling hydrograph at all tributaries and
on cloudy days and/or at late afternoon to evening.
Underwater photographs found and
confirmed that steelhead fry emergence occurred by late May at one of the
intermittent tributaries and at another with side channels going intermittent
by May. Steelhead fry were likely
present dating to at least mid May but they could not be clearly identified in
the photographs. It is important to note
that photographs were not taken prior to mid May which might have captured even
earlier emergence.
The one stream attribute
identified that resulted in more intensive steelhead spawning was that of a
well contained channel with least difference between wetted and bankfull widths
(bankfull width/wetted width ratio) during the steelhead spawning period. This was found to be the case at the entire
length of the one stream with the greatest steelhead redds/km, and at one
particularly heavily used side channel of a stream that otherwise had a broad
and actively moving mainstem channel.
Shifts in the monthly pattern of
air temperatures and precipitation since 1909 (Tables 4 and 5) were examined as
were relevant streamflows dating to 1928 (Table 6). Shifts are occurring that are particularly
correlated with the steelhead spawning period of January to May. Air temperature trends include warmer air
temperatures in January, less variable temperatures in February, and cooler
temperatures in the remaining months. More precipitation now occurs in each of
the months except February, as well as greater average streamflow, with the
exception of February and May.
Historically peak spring streamflow occurred in May, now peak spring
streamflow occurs in March. Steelhead spawn timing must adapt to these climate
related changes. It is important to note
that the one month with least change is February. It may provide an important temporal point of
climatic stability for steelhead spawning that has remained little changed the
past 100 years.
For historic comparison, three of
the five Mid Skagit tributaries regularly surveyed in 2014 were also surveyed
in 1978-1981. The steelhead redds/km
found in 2014 were 35%-78% of that in the earlier time period (Table 7). Mid Skagit tributaries are now apparently
much less productive for wild steelhead than was the case about 35 years
ago. This may not necessarily be
explained by habitat loss and/or ocean conditions alone. It may be at least as significantly related
to loss of steelhead life histories (such as early run-timing and/or early
spawning) that can no longer fill formerly productive and widespread habitat
that is increasingly left depleted or vacated.
At that earlier time, the smaller tributaries were found to support
65-80% of all steelhead spawning in the Skagit basin despite an average
escapement estimate of 5,700 wild steelhead, over 63% less than the preliminary
escapement estimate of over 9,000 in 2014 (Table 8). If tributaries were at former productivity
levels, presumably the 2014 wild steelhead return would have been greater than
it was. Identifying and resolving the
present limitations for tributary steelhead productivity in the Skagit basin
may lead to considerable wild steelhead recovery progress.
The 67% of hatchery steelhead
found spawning in Mid Skagit tributaries prior to March 15th was of
particular concern that would be anticipated to be most problematic for wild O. mykiss populations (that include both
anadromous and resident life histories) at tributaries typified by warmer
winter flows and/or intermittent hydrology.
Four of the five tributaries regularly surveyed had these
characteristics. Regarding future
genetic studies that may occur, it will be important to recognize the early
period of time when steelhead spawning can occur in Skagit basin tributary
streams with subsequent early fry emergence.
To indicatively represent the hatchery signal sampling should occur that
includes the earliest fry stage prior to significant depletion through natural
selection from early May to mid June.
After that time increasingly high depletion of hatchery and hybrid fry
whose life histories may well exclude effective movements from intermittent
streams or stream sections would be anticipated. In general, hatchery heritage would be
anticipated to result in increased fry/parr loss over time due to greater
vulnerability to predation, or due to other factors that commonly limit
hatchery related characteristics to survive as well as wild. The least effective time to find a hatchery
genetic signal would be anticipated in juvenile sampling occurring from July
onward, and least of all from returning adult steelhead.
These independent 2010-2014 Mid
Skagit tributary surveys provide a baseline for the
full period of steelhead spawning
that has otherwise been lacking from which to monitor wild steelhead
escapements, the hatchery component of the escapements, and how the steelhead
spawning is variable in time and quantity by individual tributaries that have
similarly variable characteristics that need to be understood. Recovery planning can be anticipated to be
more effective if it is based on information that effectively represents the
reproductive ecology of wild O. mykiss
populations that include both anadromous and resident life histories. This can occur with further refinement of
this spawning survey and reproductive evaluation template that includes habitat
differences along with the differing adaptive life history strategies of the
fish themselves.
